93. LEMNACE^. 94. POTAMOGETONACEiE. 349 



with not more than 3 large seeds. — Thickets in the Undercliff, 

 Isle of Wight. Mr. Hambrough. P. VI. E. 



Order XCIII. LEMNACE^. 



Fl. moncBcious, 2, in a spath, but without aspadix. Perianth 

 0. Stam. 1 — 2, distinct. Ovary 1-celled. Style short. Stigma 

 simple. Fr. bladdery, not bursting. Seeds with a coriaceous 

 ribbed testa. — Floating, leaflike, small ; no distinction of st. or 

 leaf. 



1. Lemna. Spath membranous, urn-shaped. Stam. 1 — 2. 

 Anth. 2-celled, didymous (cells bilocular?). — Fl. from just 

 below the edge of the frond. Increasing chiefly by buds. 



1. Lemna Linn. Duckweed. 



1. L.trisv,lca('L.);frondsthm\)elhic\d elliptic-ZnKCeoZc^e tailed 

 at one end serrate at the other, roots solitary. — E. B. 926. R. 

 vii. 15. — Roots tipped with a sheath. Fronds half an in. long, 

 proliferous at right angles. " Filaments recurved, filiform." 

 Schleid. Plants truly annual, producing gemmse which survive 

 the winter as in the other species. — Stagnant water. A. VI. 



2. L. minor (L.) ; fronds ohovate compressed opaque, roots 

 solitary. — E, B. 1 095. R. vii. 14. — Fronds 1 — 2 lines long, nearly 

 flat beneath, of a compact texture. Filaments recurved, filiform. 

 —Stagnant water. A. VI. VII. 



3. L. polyrrhiza (h.); fronds roundish-obovate compressed, 

 roots many clustered. — E. B. 2458. R. vii. 15. Spirodela 

 Schleid., Endl.— Fronds half an in. long, green above, purple 

 beneath. " Filaments narrowed below." Schleid. — Stagnant 

 water. A. Fl. have not been seen in Britain. 



4. L. gibba (L.) ; fronds obovate nearly flat above hemispheri- 

 cal and spongy beneath, roots solitary. — E. B. 1233. R. vii. 14. 

 Telmatophace Schleid., Endl. — Fronds 1 — 2 hues long, remark- 

 ably gibbous and cellular beneath. " Filaments recurved, dilated 

 in the middle." Schleid. See an excellent account of the germi- 

 nation of this plant, by Mr. Wilson, in Bot. Misc. i. 145. t. 42. — 

 Stagnant water. A. VI.— VIII. 



Order XCIV. POTAMOGETONACEiE. 



Fl. perfect or imperfect. Perianth inferior, 4-parted, or 0, or 

 replaced by a membranous spath. Stam. free, 1, 2 or 4. Ovaiies 

 4, distinct, each with 1 ovule, and 1 sessile stigma. Fr. a drupe 



